Johor state assembly speaker Mohd Puad Zarkashi has volunteered to sue Dr Mahathir Mohamad over Malaysia's loss of Pulau Batu Puteh.

Puad is taking up a challenge by Johor Menteri Besar Onn Hafiz Ghazi on Sunday for legal action to be taken against the "betrayal" that caused the country to lose the rocky outcrop to Singapore.

Puad said today that even though Onn Hafiz did not name anyone, everyone knew that Mahathir was responsible.